Transformer



Dec. 17, 1929.

s. HoRELIcVK A TRANSFORMER Filed Feb. l, 1924 N N H H .A00 MO 0N H NAO I NON Patented Dec. y"17, 1929 Unirse STATES PATENT OFFICE l SAMUEL HORELICK, OF 'PITTSBURGIL PENNSYLVANIA, ASSIGNOR TO PITTSBURGH TRANSFORMER COMPANY, A CORPORATION OF PENNSYLVANIA TRANSFORMER Application filed February 1, 1924. Serial No. 689,981.'

My invention relates to electric transformers, particularly adapted for use with different applied voltages.

It is a common occurrence in practice to provide a transformer which will be readily adapted for use not only on the circuit for which it may be intended at the time, but also for possible use on a circuit of different voltage, or for use on the samecircuit with an increased or lowered voltage. For example, a plant may have in use one circuit in which transformation from 22,000 volts to a lower voltage is being carried out and then have in use another circuit in which transformation from 33,000 volts to a'lower voltage is being Carried out, or it may be intended to increase the applied voltage in a 22,000 volt system to a 33,000 volt system. In either case in purchasing a transformer, it is desirable to have one which can readily be used on 'either the higher or lower voltage, while deriving the same volt-age from the secondary windingof the transformer in each case. In .this instance it has been common to provide a primary winding with a sufiicient number of turns adapted to receive 33,000 volts for securing the desired secondary voltage; and to provide a 2/3 tap on the primary winding so that when used on the 22,000 volt circuit, connection will be made to one terminal of the winding and to the 2/3 tap, thus giving the same secondary voltage as before. In such a case, however, the'ampere capacit-y of 2/3 of the primary winding must be greater' than the remaining third of the winding to provide for use on the 22,000 volt circuit. But when the transformer is used on the 33,000 volt circuit, this excess ampere capacity in two-thirds of the winding is unnecessary and not economically used; and when the transformer is used on the 22,000 volt circuit, onethird of the winding is out of circuit and is notused at all. f

It is thus evident that the provision of a transformer of `Vthis character requires a larger space and more expense in the windings, as well as increase in the size of the core,than would be the case if the transformer were adapted for use on only one of the two above mentioned voltages; yet the convenience and the saving in expense over the pur` chase of two transformers has been sufliciently'greatto warrant the practice above described.

The mainobject of my invention is to provide a transformer which will answer the above requirements of beingl adapted for use with 'a plurality of primary voltages and which will have a high eiiiciency in operation when used with either of the voltages'for which it is intended. Another object is to reduce the size of the transformer compared with the size previously required. Another object is to provide a transformer which will be more economical in costof construction compared with transformers of this type previously used. Another object is to provide means for conveniently connecting the windings so that the transformer [will be adapted for use with the particular voltage desired `at any time, and to also provide convenient means for changing the connections so as to be adapted for use with another voltage. Other objects and advantages of my invention will be understood from the following description and accompanying drawings which disclose preferred embodiments of my invention.

Ink applicants Patent 1,576,280, March 9, 1926,v is disclosed and claimed how certain broad aspects of thesey objects may be attained. I will now describe a method which may be employed in providing a transformer in accordance with my present invention which is adapted for use with voltages having certain ratios as will appear hereinafter, and more particularly in which coil sections adapted to work at unequal voltages respectively are preferably employed.

Fig. l represents a partial diagram of a transformer winding adapted for use with an impressed voltage V. Fig. 2 represents the same winding adapted for use with a lower impressed voltage V1. The winding in Fig. l comprises a single coil H in series with which is a group of coils the arrangement of which is as yet undetermined. I have arbitrarily assumed that the voltage impressed on the coil H in the arrangement shown in Fig. l is V1 volts. The remainder of the winding of Fig. 1 will receive V2 volts such that V1+I72=V- In the arrangement shovrn in Fig. 2 the coil H is connected directly across the low voltage line and Will in this case also have impressed upon it V1 volts. The Winding in Fig. 2 is completed by coil I connected directly across the loW voltage line. If V2=1/2V1 the Winding of Fig. 1 may be conpleted by dividing the coil I into two equal sections and connecting these sections in parallel with each other'and in series With the coil H. Similarly if V2=1/3V1 the arrangement of Fig. 1 could be completed by dividing the coil I into three equal parts and connecting them in parallel. If

the coil I should be divided into N equal parts. This may be expressed by the following equation n or N=% 0 said Figs. 1 `to 7 may be considered one coil as the same are always connected 1n series.

Equation (1) gives a solution when g2 rel n duces to a Whole number or to a fraction with one as the numerator. In other cases 1t Will `be necessary to divide the coil I into a number of sections Which is the least common multiple of V2 and V1. Assuming that this least common multiple is V2 V1, that is7 can not be reduced to simpler terms, the coil I may be divided into V2 Vl equal sections and these sections arranged in V1 parallel groups, .each comprising V2 sections connected in series, for the Fig. 1 arrangement and arranged in V2 parallel groups each comprising V1 sections in series, for the Fig. 2 arrangement.

Figs. 3 and l represent a transformer adapted for voltages having the ratio 7 to 3. In this case V1 3 That portion of the Winding to the right of Fig. 3 is therefore divided into 4X 3:12 sections. These are arranged in the manners shown in Figs. 3 and 4 to complete the Winding.

In the above cases it has been assumed that the portion H of the Winding consists of a single coil adapted to receive the lower voltage Vl in both high and loiv voltage arrangement. In certain cases it is possible to reduce the total number of coil sections and also the number of turns by employing, instead of the coil H, a plurality of coil sections which are grouped according to one arrangement for the high voltage connection and according` to a different arrangement for the low voltage connection. In Figs. 5 and 6 such an arrangement is shown in which the transformer is adapted for a higher voltage V and a lower voltage Vl. In Fig. 5 the Winding is divided into three portions in series with one another7 these portions receiving respectively V1 volts, V2 volts and Vg volts. V1 is here assumed to be equal to V 2 and the coil H of Fig. 5 is composed of two equal sections arranged in series in Fig. 5 and in parallel in Fig. 6. The voltage point X of the transformer circuit of Fig. 5 is chosen so that the relationship between the voltages Vll-Vg and V1 is a simple one namely 2 to l. If the voltage point X can be chosen so that at the same time the relationship between the voltages V', and V 3 is also a simple one, the number of coil sections of the portion H2 of the Winding and the total number of turns Will be small and these sections will be connected in series with the portion H and connected to each other in aecordance with one arrangement in Fig. 5 and connected in parallel with the portion H and connected to one another according to the different arrangement in Fig. 6. i

As illustrating the advisability in certain cases of employing the method just given, let it be supposed that We wish to design a transformer adapted for impressed voltages of 23 and 6. If the method described is connection With Figs. 1 and 2 were adopted the single coil corresponding to the coil I-I and adapted to receive an impressed voltage of 6 volts Would be employed. The remainder of the Winding would then have to consist of 102 sections arranged in six parallel groups of 17 sections in series each, for the high voltage arrangement and 17 parallel groups of this section in series each for the low voltage arrangement. The number of turns is vei'v much reduced by adopting a voltage point X of Fig. 7 which differs in potential from one terminal of the transformer by 15 volts and from the other terminal by 8 volts. In this ligure it will be seen that V'Z-tV1 bears the relation to V1 of 5 to 2. As a. result of this arrangement the entire winding consists of but 22 coil sections as against 108 by the former method With a consequent reduction in the number of turns,

It Will be noted that in all of the specilic examples above described, I make use of parallel circuits carrying different currents.

In certain cases it may be advisable to form more than two groups of coil sections with sections of each group differing from sections of another group. The extension of this CII method to the design of a transformer adapted for three or more external voltages will be evident. Figs. 9 to 11 show the simple case ot a transformer adapted tor impressed line voltages ot 5, 4 and 2. Here the ratio oit Vl to VZ is a simple one as is also the ratio of V/l to X773. i

The method underlying the 'foregoing examples ot arrangements of coil sections and selection oi relative voltages may be generalized as follows. For convenience referring to Figs. 7 and 8, it will benoted that the coil section voltage to the left ot point ai is represented by the factor 3 which is a 'factor ot the external voltage V1. The coil section voltage factor 3 goes into the group voltage VltVZ, tive times, and into the external 'voltage V1 (Fig. 8) twice. Thus there are lO coils and there may be two parallel paths of 5 coils each as in Fig. 7 or tive parallel paths ot' 2 coils each as in Fig. 8. It will be obvious that the total number ot coils in a given major group is therefore equal to the product ot the voltage across that group and the lowest external voltage, divided by the square of the coil section voltage.

It will be understood that my invention is advantageously adapted to various types ot transformers and different forms ot construction and also? to polyphase transformers as well as single phase and to single phase transformers connected in polyphase circuits. V] hen used on polyphase circuits the windings may be connected in delta, star or otherwise as desired It will be obvious that the coil sections or groups ot' coil sections, orboth, may be prof vided with special terminals and connecting means for connecting the sections and groups in various arrangements, in a manner similar or equivalent to that shown in Figs. 6 and T olf applicants patent hereinbefore referred to.

I claim:

.. A trans former for different voltages 'comprising windings sub-divided` into sections, certain of said sections having different resistance and a different number of turns from other ot' said sections, and means for connecting said sections in diiierent series and parallel arrangements, each section in all arrangemfents receiving the same current.

2. A stationary induction apparatus adapted to be employed with a plurality of dit terent external voltages comprising a winding formed ot' a plurality of coil sections, 4said sections, when the apparatus is arranged for use with a higher voltage, being arranged in two groups which are connected in series at a point in the winding having such a potential that the voltages between said point and thc terminals of the apparatus bear simple relations to a lower ot the external voltages, there beingcoil sections upon opposite sides of said point of different current carrying capacities and diiferent numbers of turns yand means for changing the series parallel relatio-nships of the coil sections of said groups to adapt the winding for use with dilierent external voltages, each coil section being adapted to work at its full capacity and each turn of the winding receiving substantially the same voltage in all arrangements.

3. A stationary induction apparatus adapted to be employe-d with a plurality of ditferentV external voltages comprising a winding formed ot a plurality of coil sections, said sections, when the apparatus is arranged for use with a higher voltage, being arranged in two groups which are connected in series at a point in the winding having such a potential that the voltages between said point and the terminals of the apparatus are different from and bear simple relations to a lower of the external voltages, there bein@ coil sections upon opposite sides ot said point ot' different current carrying capacities and diferent numbers of turns and means for changing the series parallel relationships of the coil sections 'ot' said groups to adapt the winding for use with different external voltages, each coil section being adapted to work at its full capacity and each turn ot the winding re ceiving substantially the same voltage in all arrangements. v

4. A stationary induction apparatus adapted to be employed with a plurality of ditferent external voltages comprising a winding formed of a plurality of coil sections, said sections, when the apparatus is a ranged for use with a higher voltage, being arranged in two groups which are connected in series at a point in the winding having such a potential that the voltages between said point and the terminals of the apparatus bear simple relations to a lower of the external voltages, there being coil sections upon opposite side ot said point of dillerent current carrying capacities and different numbers of turns and means tor changing the series parallel relationships of the coil sections ot' one of said groups `to adapt i the winding for use with different external voltages, each. coil section being adapted to work at its full capacity and each turn of the winding receiving substantially the same voltage in all arrangements.

5. A stationary induction apparatus adapted to be employed withl a plurality of ditferent external voltages comprising a winding formed of a plurality of coil sections, said sections, when the apparatus is arranged for use with a higher voltage, being arranged in groups which are connected in series, a predetermined number of the individual coil sections ot a given group being of a diderent current carryingcapacity than coil sections of another group and being adapted to work at a voltage which is a factor of said lower external voltage and of the voltage across said given group, the working voltage of a predetermined number of coil sections in another of said groups being different trom that of said coil sections of said given group and also a factor of said lower external voltage and of the voltage across said other group, and means for changing the relationships ot' the coil sections of said groups to adapt thc winding for use with dii'i'erent externalA voltages, each coil section being adapted to work at its full capacity in all arrangements.

6. A stationary induction apparatus adapted to be employed with a plurality of dit ferent external voltages comprising a winding formed of a plurality of coil sections, said sections, when the apparatus is arranged 'tor use with a higher voltage, being arrangedv in two groups which are connected in series at. a point in the winding having such a potential that the volt-ages between said point and the terminals of the apparatus bear simple relations to a lower of the external voltages, there being coil sections upon opposite sides oi' said point of different current carrying capacities, a predetermined number of the individual coil sections on one of said sides being adapted to work at a voltage which is a 'taeter of said lower external voltage, a predetermined number ofthe invidual coil sections onA the other of said sides being adapted to work at a. voltage different from that of said iirst mentioned side and which voltage is a 'factor of said lower external voltage and ont the voltage across the group ot coil sections of which said last named coil sections form a part, and means for changing the relationships oi the coil sections of said groups to adapt the winding for use with different external voltages, each coil section being adapted to work at its full capacity and each turn of the* winding working at substantially the same voltage in all arrangements.

7. A stationary induction apparatus adapted to be employed with at least two diferent external voltages, comprising a winding formed of a plurali' y ot' coil sections, said sections when the aliparatus is arranged Ato; use with a higher oi said external voltages being arranged in two major groups the ratio of the voltages across said groups being non-integral with either voltage as the numerator of said ratio, and the voltage across'one of said groups bearingl a simple relationv to a lower of said external. voltages.

8. A stationary induction apparatus adapted to be employed with at least two ditferent external' voltages, comprising a winding formed of a plurality of coil sections, said sections when the apparatus is arranged for use with a higher of said external voltages be-v ing arranged in two or groups the ratio ot the voltages across said groups being non-integral with either voltage as the numerator of said ratio, and the voltage across one of said groups bearing a simple relation to all o't the lower oit said external voltages.

9. A stationary induction apparatus adapted to be employed with at least two different external voltages, comprising a winding formed of a plurality of coil sections, said sections when the apparatus is arrangedv for use with a higher of said external voltages being arranged in two major groups the'ratio of the voltage across said groups being non-integral with either voltage as the numerator of said ratio, and the voltage across each of said groups respectively bearing a simple relation to a lower of said external voltages.

l0. A stationary induction apparatus adapted to be employed with at least two different external voltages, comprising a w riding formed of a plurality of coil sections, said sections when the apparatus is arranged for use with a higher of said external voltages being arranged in two maj or groups the ratio of the voltage across said groups being non-integral with either voltage as the numerator of said ratio, and the voltage across each off said groups respectively bearing` a simple relation to all of the lower of external voltages.

A stationary' inductionv apparatus oted to be employed with a plural-ity of -nal voltages, comprising a winding formed of a plurality of coil sections, said sections when the apparatus is arranged for use with the highest of said external voltages being arranged in two major groups, the coil sections of one of saidV major groups being adapted to work at a voltage different from that of the coil sections of the other major group, one of said major groups being coniposed of two minor `groups of coil sections, the voltage acrosssaid one of said major gro-ups bearing a simple relation to the voltage across one of said minor groups.

l2. A stationary induction apparatus adapted to be employed with a plurality of external voltages, comprising a winding formed of a plurality of coil sections, said sections when the apparatus is arranged for use with the highest of said external voltages being arranged in two major groups, the coil sections of one of said major groups being adapted to work at a: voltage diii'erent from that of the coil sections of the other major group, one of said major groups being com posed of two minor groups of coil sections, the voltage across one of said major groups bearing a simple relation to the voltage across each of said minor groups.

13. A stationary induction' apparatus adapted to be employed with a plurality of external voltages, comprising a winding formed of a. plurality of coil sections, said sections when the apparatus is' arranged for use with the highest of said external voltages l eing arranged in two major 0froups, the coil sectionsA of one' of said major groups being adaiited to work at a voltage different from that of the coil sections of the other major group, one of said major groups being.' composed of two minor groups of coil sections,

the voltage across said one of said major groups bearing a simple relation to the voltage across one of said minor groups, the voltage across the other of said major groups bearing a simple relation to the voltage across said one of said minor groups.

14. A stationary induction apparatus adapted to be employed with a plurality of external voltages, comprising a winding formed of a plurality of coil sections, said sections when the apparatus is arrange-d for use with the highest of said external v oltages being arranged in two major groups, the coil sections of one of said major groups being adapted to work at a voltage different from that of the coil sections of the other major group, one of said major groups being composed of two minor groups of coil sections, the voltage across said one of said major groups bearing a simple relation to the voltage across each of said minor groups, the voltage across the other of said major groups bearing a simple :relation to the voltage across one of said minor groups.

15. A stationary induction apparatus adapted to be employed with at least'two different external voltages, comprising a winding formed of a plurality of coil sections, said sections when the apparatus is arranged for use with a higher of said external voltages being arranged in two major groups the ratio of the voltage across said groups being non-integral with either voltage as the numerator of said ratio, the coil sections of one of said major groups being adapted to work at a voltage different from that of the coil sections of the other major group, said coil section voltages being respectively factors of a lower of said external voltages.

16. A stationary induction apparatus adapted to be employed with at least two different external voltages, comprising a winding formed of a plurality of coil sections, said sections when the apparatus is arrangedfor use with a higher of said external voltages being arranged in two maj or groups the ratio of the voltages across said groups being nonintegral with either voltage as the numerator of said ratio, the coil sections of one of said major groups being adapted to work at a voltage different from that of the coil sections of the other major group, said coil section voltages being respectively factors of all of the lower of said external voltages.

17. A stationary induction apparatus adapted to be employed with a plurality of external voltages, comprising a winding formed of a plurality of coil sections, said sections when the apparatus is arranged for use with the highest of said external voltages being arranged in two major groups, the coil sections of one of said major groups being adapted to work at a voltage different from that of the coil sections of the other major group, said coil section voltages being readapted to be employed with a plurality of .external voltages, comprising a winding formed of a plurality of coil sections, said y sections when the apparatus is arranged for use with the highest of said external voltages being arranged in two major groups, the coil sections of one of said major groups being adapted to work at a voltage different from u that of the coil sections of the other major group, said coil section voltages being respectively factors of a lower of said external voltages, one of said major groups being composed of two minor groups of coil sections, the voltage across one of said major groups bearing a simple relation to the voltage across each of said minor groups.

19. A stationary induction apparatus adapted to be employed with a plurality'oil external voltages, comprising a winding formed of a plurality of coil sections, said sections when the apparatus is arranged for use with the highest of said external voltages being arranged in two major groups, the coil sections of one of said major groups being adapted to work at a voltage different from that of the coil sections of the other major group, said coil section voltages being respectively factors of a lower of said external L voltages, one of said major groups being composed of two minor groups of coil sections, the voltage across said one of said major groups bearing a simple relation to the voltage across one of said minor groups, the voltage across theother of said major groups bearing a simple relation to the voltage across said one ofsaid minor groups.

20. A stationary induction apparatus adapted to be employed with a plurality of external voltages, comprising a winding formed of a plurality of coil sections, said sections when the apparatus is arranged for use with the highest of said external voltages being arranged in two major groups, the coil sections of one of said major groups being adapted to work at a voltage different from that of the coil sections of the other major group, said coil section voltages being re spectively factors of a lower of said external voltages, one of said major groups being composed of two minor groups of coil sections, the voltage across said one of said major groups bearing a simple relation to the voltage across each of said minor groups, the voltage across the other of said major groups bearing a simple relation to the voltage across one of said minor groups.

21. A stationary induction apparatus adapted to be employed with at least two .different external voltages, comprising a `Winding formed of a plurality ot' coil sections, said sections when arranged for use .wit-h the highest of said external voltages being arranged in two major groups, the coil sections of one of said major groups being adapted to Work at a voltage different from that of the coil sections of the other niajor group, the coil section voltages of the respective groups being factors of the lowest or said external voltage and of the respective voltages across said major groups, the number of coil sections in the respective major groups being equal to the product of the lowest of said external voltages and the respective group voltage, divided by Vthe square of .the coil section voltage of ,the respective group.`

22. A stationary induction apparatus adapted to be employed with at least-two dit ferent external voltages, comprising a ,winding formed of a plurality of `coil sections, said sections when arranged for use with the highest of said externa-l voltages being ar ranged in :two major groups, the coil sections of one of ,said major groups being ladapted to ,work at a voltage different from that of the coil sections of the other ,major group, the coil section voltages of the yrespective groups being factors of the lowest of said external ,volt-,age and of lthe respective voltages across said major groups, the number of coil .sections in the respective imajor groups being equal to the product of :the lowest of saidexternal voltages andthe respective group voltage, divided by the square .of :the coil section voltage of the lrespective group, the coil sections in the respective major groups being connected in such servies parallel arrangement that the number of parallel paths in the respective groups is ,equal to the lowest external voltage divided by the respective coil ASeC- tion voltage.

.SAMUEL HORELICK 

